Recent advances in the total synthesis of 2,7'-cyclolignans

Design strategy and preliminary antiproliferative investigation of a modified lignan skeleton derived from aryne and statin

The biological activities of natural products (NPs) provided precious resources for the development of new drugs. Numerous studies have shown that statins exhibit cytotoxic potential, which is now an extensive focus of investigation. Herein, a remarkably efficient method for modification of statins using hexadehydro-Diels-Alder (HDDA) arynes has been described. Notably, lactone, as the biologically active group of statins, was removed during the reaction and a novel modified lignan skeleton was generated via the Alder-ene process. Unexpectedly, these statin-derived novel chemical scaffolds exhibited moderate inhibition effects on the proliferation of cancer cells as determined by CCK-8 assays, and the IC50 values were in the micromolar range.

Accessing the synthesis of natural products and their analogues enabled by the Barbier reaction: a review

The Barbier reaction is significantly referred to as one of the efficient carbon-carbon bond forming reactions which involves the treatment of haloalkanes and carbonyl compounds by utilizing the catalytic role of a diverse range of metals and metalloids. The Barbier reaction is tolerant to a variety of functional groups, allowing a broad substrate scope with the employment of lanthanides, transition metals, amphoteric elements or alkaline earth metals. This reaction is also water-resistant, thereby overcoming the challenges posed by moisture sensitive organometallic species involving C-C bond formation reactions. The Barbier reaction has significantly found its applicability towards the synthesis of intricate and naturally occurring organic compounds. Our review provides an outlook on the synthetic applications of the Barbier reaction and its variants to accomplish the preparation of several natural products, reported since 2020.

A two carbon homologation of Friedel-Crafts alkylation enabled by photochemical alkene stitching: modular assembly of cyclolignans

Herein we report an efficient two-carbon homologated variant of Friedel-Crafts alkylation via photochemical radical alkene stitching. Readily available feedstock alkenes are used as bridges between photogenerated alkyl radicals and arenes, opening a route to γ-aryl-carbonyls for chemo-divergent access to aryltetralone and γ-lactones, a gateway to 2,7'-cyclolignans.

Intramolecular Ni-catalyzed reductive coupling enables enantiodivergent synthesis of linoxepin

A nickel-catalyzed reductive tandem cyclization of the elaborated β-bromo acetal with a dibenzoxepin scaffold was invented to strategically construct the remaining two rings in linoxepin. The generated diasterodivergent intermediates could be easily converted to both enantiomers of this unique cyclolignan molecule via facile oxidations, thus realizing enantiodivergent total synthesis of linoxepin for the first time.

New Preparation of Ferrocene Carboxylic Acid Benzotriazol-1-yl Ester

Ferrocene and its derivatives are very useful in the fields of chemistry, biomedicine and materials. Herein, a ferrocene derivative was synthesized in one step from benzotriazol-1-yl-oxytripyrrolidino-phosphonium hexafluorophosphate and ferrocenecarboxylic acid. Its accurate structure was determined by 1H and 13C NMR and further confirmed by X-ray diffraction analysis of the corresponding single crystal.

A Concise Synthesis of Sacidumlignan B

A short synthesis of racemic Sacidumlignan B was achieved for the first time. The key steps included a formal reductive coupling between the diaryl ketone and the crotyl bromide, and the subsequent Friedel–Crafts cyclization, which led to an efficient construction of dihydronaphthalene skeleton in this 2,7′-cyclolignan natural product.

Total synthesis of linoxepin facilitated by Ni-catalyzed tandem reductive cyclization

A nickel-catalyzed reductive cyclization was developed to construct the tricyclic core embedded in linoxepin, a cyclolignan with a unique benzoxepin ring. The generated diasterodivergent acetals could be converted to the...